IConvertible Interface
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Defines methods that convert the value of the implementing reference or value type to a common language runtime type that has an equivalent value.
Assembly: mscorlib (in mscorlib.dll)
The IConvertible type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | GetTypeCode | Returns the TypeCode for this instance. |
![]() | ToBoolean | Converts the value of this instance to an equivalent Boolean value using the specified culture-specific formatting information. |
![]() | ToByte | Converts the value of this instance to an equivalent 8-bit unsigned integer using the specified culture-specific formatting information. |
![]() | ToChar | Converts the value of this instance to an equivalent Unicode character using the specified culture-specific formatting information. |
![]() | ToDateTime | Converts the value of this instance to an equivalent DateTime using the specified culture-specific formatting information. |
![]() | ToDecimal | Converts the value of this instance to an equivalent Decimal number using the specified culture-specific formatting information. |
![]() | ToDouble | Converts the value of this instance to an equivalent double-precision floating-point number using the specified culture-specific formatting information. |
![]() | ToInt16 | Converts the value of this instance to an equivalent 16-bit signed integer using the specified culture-specific formatting information. |
![]() | ToInt32 | Converts the value of this instance to an equivalent 32-bit signed integer using the specified culture-specific formatting information. |
![]() | ToInt64 | Converts the value of this instance to an equivalent 64-bit signed integer using the specified culture-specific formatting information. |
![]() | ToSByte | Converts the value of this instance to an equivalent 8-bit signed integer using the specified culture-specific formatting information. |
![]() | ToSingle | Converts the value of this instance to an equivalent single-precision floating-point number using the specified culture-specific formatting information. |
![]() | ToString | Converts the value of this instance to an equivalent String using the specified culture-specific formatting information. |
![]() | ToType | Converts the value of this instance to an Object of the specified Type that has an equivalent value, using the specified culture-specific formatting information. |
![]() | ToUInt16 | Converts the value of this instance to an equivalent 16-bit unsigned integer using the specified culture-specific formatting information. |
![]() | ToUInt32 | Converts the value of this instance to an equivalent 32-bit unsigned integer using the specified culture-specific formatting information. |
![]() | ToUInt64 | Converts the value of this instance to an equivalent 64-bit unsigned integer using the specified culture-specific formatting information. |
This interface provides methods to convert the value of an instance of an implementing type to a common language runtime type that has an equivalent value. The common language runtime types are Boolean, SByte, Byte, Int16, UInt16, Int32, UInt32, Int64, UInt64, Single, Double, Decimal, DateTime, Char, and String.
If there is no meaningful conversion to a common language runtime type, then a particular interface method implementation throws InvalidCastException. For example, if this interface is implemented on a Boolean type, the implementation of the ToDateTime method throws an exception because there is no meaningful DateTime equivalent to a Boolean type.
The common language runtime typically exposes the IConvertible interface through the Convert class. The common language runtime also uses the IConvertible interface internally, in explicit interface implementations, to simplify the code used to support conversions in the Convert class and basic common language runtime types.
In addition to the IConvertible interface, the .NET Framework allows you to define a custom type converter to convert user-defined data types to other data types. A type converter is a class derived from System.ComponentModel.TypeConverter. It is associated with the class for which it serves as a type converter by applying the System.ComponentModel.TypeConverterAttribute attribute to that class.
Notes to ImplementersIf you implement the IConvertible interface, your implementation will be called automatically by the ChangeType method if the Object parameter is an instance of your implementing type and the Type parameter is a common language runtime type.
Most IConvertible methods have a parameter of type IFormatProvider. This parameter commonly represents either the current culture (CultureInfo.CurrentCulture) or a specific culture. For the most part, the IConvertible implementations of the base types ignore this parameter. However, you can choose whether to use it in your code.
The following example demonstrates an implementation of IConvertible for a Complex number class, allowing it to be cast first as a Double and then calling the static Convert members on that Double.
Module Example Public Class Complex Implements IConvertible Private x As Double Private y As Double Public Sub New(ByVal x As Double, ByVal y As Double) Me.x = x Me.y = y End Sub 'New Public Function GetTypeCode() As TypeCode Implements IConvertible.GetTypeCode Return TypeCode.Object End Function Function ToBoolean(ByVal provider As IFormatProvider) As Boolean Implements IConvertible.ToBoolean If x <> 0 Or y <> 0 Then Return True Else Return False End If End Function Function GetDoubleValue() As Double Return Math.Sqrt((x * x + y * y)) End Function Function ToByte(ByVal provider As IFormatProvider) As Byte Implements IConvertible.ToByte Return Convert.ToByte(GetDoubleValue()) End Function Function ToChar(ByVal provider As IFormatProvider) As Char Implements IConvertible.ToChar Return Convert.ToChar(GetDoubleValue()) End Function Function ToDateTime(ByVal provider As IFormatProvider) As DateTime Implements IConvertible.ToDateTime Return Convert.ToDateTime(GetDoubleValue()) End Function Function ToDecimal(ByVal provider As IFormatProvider) As Decimal Implements IConvertible.ToDecimal Return Convert.ToDecimal(GetDoubleValue()) End Function Function ToDouble(ByVal provider As IFormatProvider) As Double Implements IConvertible.ToDouble Return GetDoubleValue() End Function Function ToInt16(ByVal provider As IFormatProvider) As Short Implements IConvertible.ToInt16 Return Convert.ToInt16(GetDoubleValue()) End Function Function ToInt32(ByVal provider As IFormatProvider) As Integer Implements IConvertible.ToInt32 Return Convert.ToInt32(GetDoubleValue()) End Function Function ToInt64(ByVal provider As IFormatProvider) As Long Implements IConvertible.ToInt64 Return Convert.ToInt64(GetDoubleValue()) End Function Function ToSByte(ByVal provider As IFormatProvider) As SByte Implements IConvertible.ToSByte Return Convert.ToSByte(GetDoubleValue()) End Function Function ToSingle(ByVal provider As IFormatProvider) As Single Implements IConvertible.ToSingle Return Convert.ToSingle(GetDoubleValue()) End Function Overloads Function ToString(ByVal provider As IFormatProvider) As String Implements IConvertible.ToString Return "( " + x.ToString() + " , " + y.ToString() + " )" End Function Function ToType(ByVal conversionType As Type, ByVal provider As IFormatProvider) As Object Implements IConvertible.ToType Return Convert.ChangeType(GetDoubleValue(), conversionType, provider) End Function Function ToUInt16(ByVal provider As IFormatProvider) As UInt16 Implements IConvertible.ToUInt16 Return Convert.ToUInt16(GetDoubleValue()) End Function Function ToUInt32(ByVal provider As IFormatProvider) As UInt32 Implements IConvertible.ToUInt32 Return Convert.ToUInt32(GetDoubleValue()) End Function Function ToUInt64(ByVal provider As IFormatProvider) As UInt64 Implements IConvertible.ToUInt64 Return Convert.ToUInt64(GetDoubleValue()) End Function End Class Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim testComplex As New Complex(4, 7) WriteObjectInfo(outputBlock, testComplex) WriteObjectInfo(outputBlock, Convert.ToBoolean(testComplex)) WriteObjectInfo(outputBlock, Convert.ToDecimal(testComplex)) WriteObjectInfo(outputBlock, Convert.ToString(testComplex)) End Sub Sub WriteObjectInfo(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal testObject As Object) Dim typeCode As TypeCode = Type.GetTypeCode(testObject.GetType()) Select Case typeCode Case typeCode.Boolean outputBlock.Text += String.Format("Boolean: {0}", testObject) & vbCrLf Case typeCode.Double outputBlock.Text += String.Format("Double: {0}", testObject) & vbCrLf Case Else outputBlock.Text += String.Format("{0}: {1}", typeCode.ToString(), testObject) & vbCrLf End Select End Sub End Module
